ARABIDOPSIS RESEARCH ROUNDUP: APRIL 14TH

14th Apr 2016

This week Arabidopsis Research Roundup contains two studies that originate at the University of Birmingham. Firstly George Bassel kindly provides an audio description of a study that looks at the processes regulating seed germination. Secondly Juliet Coates leads an investigation into the function of evolutionarily conserved ARABIDILLO proteins. Elsewhere is a University of Edinburgh study into the tissue-specificity of PhyA responses and lastly an investigation of the phytotoxic effects of Cerium nanoparticles.

George Bassel (Birmingham), GARNet PI Jim Murray (Cardiff) and Jeroen Nieuwland (South Wales) are the leaders of this study that investigates the activation of the root meristem during germination, a process that requires de novo GA synthesis. Using hormone applications and genetic analysis the authors show that root meristem can begin elongation independent of germination, which is defined as occurring following both testa rupture and radicle protrusion. KRP6 is a cell cycle regulator and partially represses activation of the cell cycle by GA so krp6 mutants germinate more rapidly. Overall this study concludes that the cell cycle can uncouple the interactions of GA and ABA that act to conclude germination and promote root meristem elongation.

This study comes exclusively from the University of Birmingham and is led by Juliet Coates. This group investigates the role of Armadillo-related ARABIDILLO proteins on branching processes across plant species. In the moss Physcomitrella patens these proteins are linked to the action of the hormone ABA on spore germination, which converges with a role for the proteins in Arabidopsis seed germination. Importantly both P.patens and Selaginella moellendorffii ARABIDILLO proteins are able to substitute for native proteins in Arabidopsis, demonstrating their conserved function. The authors conclude that these proteins were co-opted into the regulation of both sporophytic and gametophytic processes early in plant evolution.

Ferenc Nagy (Edinburgh) is the corresponding author of this Hungaro-German study that focuses on how phytochrome responses are mediated in a tissue-specific manner. Considering that phyA is expressed throughout plant tissues it remained a mystery as to how the PhyA responses are able to control plant development. This study used tissue-specific promotors to drive PHYA production in a variety of tissues and discovered that expression in a limited number of tissues is able to regulate flowering time and root growth. In addition they find evidence for the intercellular movement of PhyA. The authors conclude that the PhyA response is partly controlled by a mix of tissue-specific expression and the regulation of key downstream factors in a tissue-autonomous cell activity.

This Sino-UK-Australian study is led by Fang-Jie Zhao at Rothamstead Research. They investigate the uptake and phytotoxicity of commonly used (in consumer products) cerium oxide nanoparticles (CeO2-NPs) into Arabidopsis. At high concentrations the NP component, but not the Ce ions, were shown to have toxic effects on plant growth. These CeO2-NPs were taken up and translocated to the shoot where they aggregate in needle-like particles. This movement was independent of the type or concentation of Ce. The authors suggest this represents important information for the environmental considerations linked to the use and disposal of this type of NPs.